Alkaloids - complex organic nitrogen-containing basic compound of alkaline nature, which have strong physiological effects on the body. Got its name from the arabic word "alkali" (lye) and greek word "eidos" (similar). Their chemical structure is diverse and complex. The alkaloids are found in the form of salts of organic acids - oxalic, malic, citric, dissolved in the cell sap (morphine, caffeine, atropine, brucine, nicotine, etc.), and are the most important group of biologically active substances from which is the largest number of highly therapeutic drugs. Opening of the alkaloids in the early XIX century is compared by value for medicine with the discovery of iron for the world culture. Currently, approximately 5000 different isolated alkaloids are presented in plants in the form of organic and sometimes inorganic acids.

Alkaloid plants are account for 10% of world flora. These are complex chemical compounds, differ by diverse chemical composition and structure. Isolated from plants, they are, in most cases, crystalline substance is colorless and odorless, usually bitter. The alkaloids are found mostly in flowering plants, may be in all organs of the plant or selectively accumulate in all parts of the plant, but more often dominated by only one organ, such as the tea leaves in the grass celandine, Indian fruit intoxication in rhizome scopolia, cinchona bark in some others. Their content is usually small - from traces to 3.2% (on a dry weight of the plant) at different stages of development of the plant alkaloid the content varies, reaching a maximum in most stages of budding and flowering. Characterized by a significant therapeutic effect, they are a group of drastic. Some alkaloid plants are extremely poisonous. One of the most powerful plant poisons - arrow poisons curare, which is a mixture of alkaloid plant extracts. However, alkaloids, taken in small doses, are often the drugs, and almost all poisonous plants are used as medicine. Admission of alkaloid drugs are allowed only in the appointment and under the supervision of a physician.

Most alkaloids has high biological activity, they are mainly characterized by the selective effect in relation to the different organs of the body, which determines their widespread use in clinical practice. Previously it was considered that plants alkaloids are produced as waste. Now it is proved that the alkaloids are not passive entities that do not participate in the metabolism of plant cells. Instead, they synthesized by a plant and it is used again for the construction of other components of its cell. Some authors attribute to the alkaloids active role of causative agent of poison of (physical and chemical) processes in a plant cell, but if this were so, then the alkaloids should occur in all plants. However, until now they have been found in a relatively small number of plants, mainly in higher plants (periwinkle, belladonna, hemlock, aconite, larkspur, poppy, coffee, cocoa, Securinega, tea, Potbelly, ephedra, etc.). The largest number of them is found in beans, poppy, nightshade, buttercup, Chenopodiaceae, Asteraceae plant families. In the other groups - algae, fungi, mosses, etc. - they are rare. Most of the plants in their composition contain not one, but several alkaloids. Thus, in ergot are revealed over 30 different alkaloids and Rauwolfia serpentina - about 50. Mostly, one plant has a quantitatively predominant one or 2-3 alkaloid, and the other ones are contained in smaller amounts. Number of alkaloid plants increases as they are discovered. Of the 21,000 species of alkaloids is investigated so far less than half. In many plants, despite the most thorough search, alkaloids are not found. The content of these substances in one and the same plant depends on the time of year and phases of development. They are few in the young plant, then their number increases, reaching its maximum at the time of flowering, and then again are on the decline, but this rule has a number of exceptions. There are differences in the accumulation of alkaloids plants growing under different climatic conditions. The harsh climate of the north, apparently, unfavorable climate to form alkaloids and tundra flora is poor in plants containing alkaloids. Usually rich in alkaloids are plants of humid tropical climate. Warm weather contributes to the content of alkaloids in plants, cold weather - slows, and when frost alkaloids in plants do not accumulate. For example, in the Caucasus, the aboveground part of hellebore after frost, animals eat without further poisoning, and in Central Asia after the frost camels eat anabasis. Alkaloids content is changed even during the day. Puffy Lobelia has a number of them in the night by 40% more than in the afternoon. Incisions of opium poppy capsules in the evening give a higher yield of opium and its content of alkaloids is higher. Studies have shown the benefits of halophytes fees Richter in the early morning and at night. Indifferent to the content of alkaloids and altitude factor. It is found that each species has its optimum height. In flat-leaved ragwort largest number of alkaloids accumulate at an altitude of 1800-2000 m above sea level (ragwort is found in the mountains at an altitude of up to 2,500 m), after which the alkaloid content is reduced. This phenomenon is observed in the cinchona tree, herb, ephedra. An important factor is the soil conditions. For example, a hodgepodge Richter, growing on sand, gives about 1% alkaloids, and grown up on clay soil contains only a trace of them. In cultivated plants is observed increase in the content of alkaloids in making nitrogenous fertilizers. Has a meaning intraspecific (individual) variability. There is a significant difference in the content of alkaloids in plants of the same species growing in the same conditions, depending on the individual properties of plants. Fluctuations in the amount of alkaloids are identified as the drying and storage of raw materials. The alkaloids are dried in artificial driers at 50-60 º C. It can be dried a dry under the iron or tiled roof on attics, laying a thin layer of raw materials. In slow drying unstable alkaloids is decomposed. Alkaloid content is also decreased during storage of raw materials in damp areas. Storage is made with care, in a dry and well-ventilated area, use of medicinal plants containing alkaloids are made ​​in compliance with the shelf life of raw materials. There is evidence of a definite pattern between the ability to synthesize alkaloids and selectively accumulate certain macro-and trace elements: cobalt, copper and manganese, for example, accumulate in the herb and poppy. Plant cell contains alkaloids in dissolved form, but can be easily recovered as a colorless crystalline solid. Only few alkaloids do not form crystals, and even fewer amount can be in a liquid state (e.g., the well-known nicotine). Alkaloids are usually not soluble in water, but readily form salts with various acids, soluble in water. The taste of alkaloids is very bitter. Alkaloid raw materials used to make tinctures, extracts, but the most common way to use - it is selection of individual alkaloids or the amount of alkaloids in the form of salts. Medicines made ​​from alkaloid plants, stimulate cell division, increase blood pressure, increase the overall metabolism, improve the secretion of gastric juice, have physiological effects on the nervous system. The alkaloids have a very wide range of pharmacological effects, actively influence the cardiovascular, mediator, muscular, endocrine and other systems that have a wide therapeutic effect - antispasmodic, analgesic, sedative and aphrodisiac. The alkaloids stimulate the central nervous system, have hypertensive and hypotensive, cholagogue, vasodilator and vasoconstrictor properties. They are part of an expectorant drugs and choleretic action, and also serve as a source for the synthesis of steroid hormone drugs. All these possibilities of alkaloids are related to their complicated and diverse chemical composition. In the body of a man alkaloids can be divided into the following groups: sedative central nervous system, stimulating (enhancing activities) CNS; hypertensive (blood pressure rises): antihypertensive (blood pressure lowering); a vasoconstrictor, vasodilator, affecting neurotransmitter systems, affecting the functional state of the musculoskeletal system. Medicinal plants and raw materials, containing alkaloids with nitrogen in the side chain: horsetail ephedra. Medicinal plants and raw materials containing alkaloids with pyrrolidine and piperidine rings (tropane derivatives): belladonna ordinary, black henbane, datura ordinary. Medicinal plants and raw materials containing alkaloids - derivatives of Quinolizidin: thermopsis lanceolata; isoquinoline derivatives: celandine, sea poppy, opium poppy, indole derivatives: Rauvolfia serpentina, lesser periwinkle, Catharanthus roseus. Medicinal plants and raw materials, containing steroidal alkaloids: Veratrum lobelliánum. Steroidal alkaloids are steroidal compounds which combine the properties of both alkaloids and steroidal saponins. Like saponins, are hydrolyzed on sugar and aglycone, have surface and hemolytic activity. Steroidal alkaloids are widely distributed in plants of the nightshade family, in different species of nightshade, especially lobular, containing steroidal glycoalkaloids. Close steroidal glycoalkaloids were found in the tops of potatoes, tomatoes, eggplant, red pepper, black nightshade and in bittersweet nightshade. These herbs during processing may give solasodin aglycone and other steroids, suitable for the synthesis of cortisone. Steroidal alkaloids are also characteristic of the genus hellebore.